Societies and Academies

Abstract

LONDON. Institute of Metals, Sept. 14 (Annual Autumn Meeting, Zurich).—H. Waterhouse and R. Willows: The effectsof cold-rolling and of heat-treatment on some lead alloys. The hardness numbers of the cast alloys ranged from 5 to 18 Brinell. Cold-rolling hardened the soft alloys and softened the hard alloys, the hardness immediately after cold-rolling lying in all cases between 8 and 11 Brinell. Most of the alloys, especially those containing cadmium and antimony, were re-hardened to approximately the ‘as cast’ hardness by suitable heat-treatment, quenching and ageing. Certain alloys age-hardened after air-cooling or even more restrained cooling from the heat-treatment temperature. The age-hardness persists for several months at least, but is destroyed by severe cold-working and self-annealing.—H. Sutton and L. F. Le Brocq: The protection of magnesium alloys against corrosion. Of the methods of protection examined the most promising appeared to be that of chemical treatment of the surface followed by the application of lanolin or a suitable enamel.—D. G. Jones, L. B. Pfeil, and W. T. Griffiths: Nickel-copper alloys of high elastic limit. The elastic limit is low in substantially pure nickel-copper alloys in the fully annealed and in the cold-drawn conditions, but high elastic limits are developed in all compositions as a result of low temperature heat-treatment following cold-working. High elastic limits may also be produced in nickel-copper alloys containing small amounts of such elements as silicon, which render the alloys susceptible to heat-treatment.—D. Hanson and I. G. Slater: Unsoundness in aluminium sand-castings. (1) Pin-holes: their causes and prevention. To eliminate pin-holes treatment with nitrogen or with chlorine is sometimes successful, but cannot always be relied upon to produce castings perfectly free from pin-holes; titanium tetrachloride is effective with ‘Y’-alloy, but was found to be less certain with other alloys, although the grain-refinement which it produces may make the pin-holes very small without reducing the total volume of the cavities. The most generally successful method is treatment with a mixture of equal parts of nitrogen and chlorine, by means of which all the alloys examined could be made practically sound by a treatment of twenty minutes' duration at 700° C.—(2) The effects of using metal previously subjected to corrosive conditions. The extent and amount of unsoundness produced depends upon the type and time of exposure, and also upon the particular alloy examined. The suggestion is made that the deterioration is the result of electrolytic action on corrosion, involving the liberation of hydrogen in the nascent state which is absorbed by the metal. On re-melting and casting, the hydrogen is evolved in the molecular condition and produces pinholes.—William Hume-Rothery: The macro-etching of aluminium-silicon alloys. The macrostructure of aluminium-silicon alloys can be revealed satisfactorily by means of a solution of cupric chloride containing 150–160 gm. per litre. Etching is carried out by immersing the specimen several times in the copper chloride solution, the deposit of copper being removed between each immersion. A final brightening can be obtained by treatment with a dilute solution of chromic acid.—J. E. Newson and A. Wragg: Note on the failure of a high-strength brass. The reeling process for straightening, after extrusion, in the case of a brass with a high yield-point, is responsible for residual stresses of such an order that failure due to internal cracking may result during storage or on subsequent machining.